Work has progressed in several areas: (1) the development of improved statistical methods for analyzing hormone data across the menstrual cycle in relation to characteristics of the woman and menstrual cycle; (2) the development of improved methods for assessing the relationship between hormone trajectories and pregnancy outcomes; (3) the development of methods for searching for optimal rules for timing intercourse to achieve conception using data on timing in the cycle and vaginal secretions; and (4) application of these methods to data from an Italian multi-center fecundability study collecting detailed records for women in natural family planning centers. We found that data on progesterone levels following ovulation are highly predictive of early pregnancy loss and that the shape of the trajectory can be used to predict risk of early loss soon after implantation. We have also found that simple rules based on timing of intercourse on days in a mid-cycle window having particular types of secretions can substantially reduce time to conception, reducing need for assisted reproductive intervention with associated costs and health risks.